Physicists at the University of New South Wales have created a transistor composed of a single atom, which is an amazing feat of nanoengineering, and could provide a better foundation for scalable quantum computing. The technique and experiment have been published in Nature Nanotechnology.
The transistor itself is composed of a single phosphorous-31 isotope, which has been precisely placed on a base of silicon using a Scanning Tunneling Microscope in an ultra-high vacuum chamber. What’s particularly amazing about their technique is that they were able to position the individual phosphorous atoms precisely. The atom was confirmed to be exactly where it needed to be. Considering that most single-atom devices have a positioning margin of error of about 10 nm, that’s an impressive accomplishment.
“Our group has proved that it is really possible to position one phosphorus atom in a silicon environment – exactly as we need it – with near-atomic precision, and at the same time register gates,” said lead researcher Dr. Martin Fuechsle in a press release.
Some physicists have conjectured that the two possible nuclear spins of P-31 make it ideal for use as the basis for solid-state quantum computing. That’s especially true because if phosphorous and silicon are used, it’s conceivable that techniques used are compatible with CMOS systems used in today’s computers.
Despite the small size of the transistor, the team was able to confirm that the electrodes present on the silicon were contacting the transistor, and also confirmed that they were able to successfully change the quantum states of the atom – which means that it can be successfully used as a transistor.
As amazing an achievement as this is, this is only the start of providing a basis for either conventional or quantum computing. Researchers will need to build off of this technology to develop chips comprised of many P-31 transistors that are able to be used for computation. Even once that’s achieved, we’re still a long way from using chips based on this transistor in your home. Scanning Tunneling Microscopy is a pretty powerful tool for positioning individual atoms, but it’s also incredibly expensive to use as a basis for manufacturing.
That said, I’m very excited about the trend of potential quantum computing that uses cheap materials, such as silicon and phosphorous, as a base for materials. From an economic standpoint, that obviously has some advantages over more expensive materials such as superconductors or diamonds, which have been used in other quantum computation applications. It’ll be interesting to see how this develops over the next few years.
In the meantime, if you want a little more background on the transistor, you can see a video that UNSW put together below:forbes.com